Crank-case-venting means for pneumatic tools



July 6 1926. 1,591,539

A. LEVEDAHL. ET AL CRANK CfiSE VENTING MEANS FOR PNEUMATIC TOOLS FiledNdv. 8, 1923 ja /2722715 fire L j; euc cZa/z L/ Fatented duly 6, flQZfi.

AXEL LEVEDAHL AND REINHOLD A. NORLING, OF AURORA, ILLINOIS, ASSIGNORS TOINDEEENDENT PNEUMATIC TOOL COMPANY, OF CHICAGO, ILLINOIS, A CORPORA-TION 01E DELAWARE.

. flo CRANK-CASE-VENTING MEANS FOR PNEUMATIC TOOLS. i

Application filed November 8, 1923. Serial No. 673,469.

tons and the cylinder bores open into the crank case. The crank and gearcases being' united, all the moving parts are lubricated by simplyfilling the gear and crank cases with suitable lubricant, mostly slowflowing oil or grease, and lubrication of the parts is elfected by whatis called a splash system. These tools in operation are placed and heldin various positions, up, down, horizontal, and at angles, depending onthe lay of the work. It therefore follows that the lubricant fromgravity accumulates in various places according to the positions of thetool. The inner end of the valve mechanism opens into the gear case andcompressed air used in operating the tools leaks into the crank casefrom the pistons and valves. Unless prevented, there wouldjbe anundesirable accumulation of air pressure in the crank case. Should aplain hole he made in the crank case for venting purposes, there wouldalways be some position of thc tool where the lubricant would coverthcf'l' ol'e and be forced out of the case as thepres s tii'e thereinincreased.

The main object of our invention is to avoid this diliiculty byproviding a venting means allowing air to escape, yet keeping thelubricant back.

Another object of our invention is to apply the air venting means to thecrank shatt and use the centrifugal forces set up on its rotation tothrow the lubricant, which is heavier than air away from the ventingmeans, thus allowing the air to escape but preventing the lubricantfollowing.

- i A further object of our invention is to employ in the air vent avalve device which will automatically close to prevent the escape oflubricant thercthrough whenever the tool is held or placed while idle ina position allowing the lubricant to collect by gravity on and about thevent moans.

Other and further objects and advantages of our invention will appearl'rom the following s 'iccilicutiirn, in connection with thearrouipanying.drawings. in whicl1r--- Fig. l is a side view of aportable piston actiuitcd air drill having incorporated there in an airventing means of our invention;

cal sectional view taken through the upper end of the crank shaft andits case to show in detail the air venting structure;

Fig. 3 is a top plan view, partly in horizontal section, of the cap ofthe air venting structure; and

Fig. 4 is a horizontal sectional view taken on line 44 of Fig; 2.

Fig. 1 shows a portable pneumatic drill of 'the type to which ourinvention is particularly applicable. This tool has an outside case 1carrying on one side a handle 2 and on the other side a combined handleand throttle valvev 3, through which compressed air is supplied to thetool for operating the same. The spindle chuck 4 at one end of thetoolcarries a twist drill 5. At the opposite end of the tool there is a.screw feed 6, as usual in tools of this character.- The case 1 isprovided on each side with a pair of parallel cylinders 7, 7 only onepair being shown in the drawings. 'These cylinders are arranged V-type,and in them work singleacting pistons 8 (only one being shown) connectedby connecting rods 9 to a crank shaft 10, the latter construction beingillus trated in Fig. 2.-

When drilling downward, as shown in .Fig. l, the crank shaft 10 isupright or vertical, as in Fig. 2, and has its upper endjournal lLin anantifriction bearing 12 of the roller ,type in the top extension or lug13 on the crankcase 14. The latter is a part of or is carried by thecase 1 of the drill, depending on the design of the same.

The end journal 11 is made hollow or drilled out to provide a centralpassage or bore 15 opening outward through the upper end of the journal.The lower end of the passage. 15 communicates with a hole 16 drilled orotherwise formed in the arm 17 of the crank shaft adjoining the crankjournal 1].. The hole 16 is preferably made at an angle to the crankjournal 11, of about and is of a size to receive the inner end of ashort tube 18, which extends toward and [cu-minutes short of itsadjacent connecting rod 9 so as to be free of the latter.

The passageway through the tube 18 isend of the tube 18 by a stop pin 21carried by the tube and extending part way across the passagewaythereof, as shown.

The extension 13 is open atits upper end to permit the assembly of thecrank journal 11 and its antifriction bearing 12. Said extension 13 isclosed by .a cap 92" provided in its skirt, part 23 with internal screwthreads to engage external screw threads on the lug or extension 13.Over the bearing 12 is placed a discshap d plate 2-t held in place by anannular shoulder 25 on the inside of the cap 22, as shown in Fig. 2.This plate 2st also extends over the upper end of the crank journal 11and forms an end thrust plate for the crank shaft and its bearing 12. v

The end plate 21 is apcrturcd at. its center to receive a tube 26attached to the same permanently, as by having the edge of the plate/.24around the aperture engage in an annular channel 27 at the adjacent endof the tube. Said tube 26 extends down into the bore 15 in the. crankjournal .11 and terminates adjacent the inner end of the tube 18, asshown in Fig. E2. The screw cap 22, end plate 24, and tube. 26 are heldstationary. A packing 18 may be used around the tube 26 and the crankjournal 11., as shown. The shoulder 25 spaces-- the top portion of thecap 22 from the upper end of the tube 26 and provides an air receivingchamber 29 which opens to the atmosphere through one or more exhaustholes or ports 30 in the cap, as shown in the drawings.

In use, the. drill may be held in various working positions, dependingon the lay of the Work. 'hen the drill is held in the position shown inFigs. 1 and 2, the end journal 11 is uppermost and the drill bit 5 andthe venttube 18 both cxtcnd downward with the stop pin 31 below the ballvalve 20. In this position, when the. drill is idle, the ball valve ill)will autoinatically unseat and come to rest. against the stop pin ll'bythe force of gravity. When the drill is operated in this position,centrifugal forces which iii'e set up by the rotation of the crank shaft10 will also co-oporate to retain the va lve 20 in its unseated positionand allow for viintin; of the crank case through the open tubcs 18, 26and the outlet ports 30 in the cap 252.

\Vhen the tool is held in its invertedposition, that is, with the endjournal ll lowermost, the drill bit 5 and the tube 18 Willlmtll mintupward. In this position, the ball valve 20 willfwhcn the drill is idle,automatically seat itself and close the vent by the force of gravity.\Vhcn the tool, ho\\'- ever, is operated in this inverted position,centrifugal forces which are set up by rotation of the crank shaft 10will automatically unseat the valve and retain thodat'ter in itsunscated position against the stop 21. during the operation of the drillfor venting of the crank case through the open tubes as before.

hen the-drill is. held in a position with the drill bit 5 and crankshaft 10 horizontal, the end journal 11 will be likewise disposed, andthe valve 20 will automatically seat by gravity should the crank shaftbe stopped with the tube 18 above the axis of the shaft. Starting thedrill with the crank shaft in this position, the valve 20will beautomatically unseat'ed to open the vent by centrifugal forces set up onthe rotation of the crank shaft. Should the crank shaft be stopped whilethe tool is held in-this horizontal position with the tube 18 below theaxis of the shaft, the ball valve will auto matically unseat by gravity,and in starting the drill from this position of 'the tube 18,centritt'ugal forces set up on the rotation of the crank sha t't willco-operate with gravitto hold the valve 20 open and vent the eran case.

Should the drill .be held in any position at an angle, either up ordown, to the several specified positions mentioned, the valve 20 willbecome automatically unseated either by gravity or centrifugal forces,depending on whether the tube 18 extends upward or downward, as will beapparent; centrifugal forces, however, playing an important part ineither.automatically unseating, the valve or co-opcrating with gravityto retain the valve nnseated during the operation of the tool should thecrank shaft be started from a position with the valve initially openedby gravity.

By connecting the tube 18 to the crank 17 at an angle of substantially45 to the axis of the shaft 10 (as shown in Fig. 2), a longer tube maybe used in the clearance space between the crank 17 and the adjacentconnecting rod 9. This better accommodates the valve 20 and permits thesame to be larger than if a shorter tube parallel to the axis of theshaft was used. This arrangement of the tube adapt-s it to a tool ofthis kind, and it is carried in position not, hindering the. operationof the adjacent moving parts. The lubricant being heavy will not beforced out with the air because any lubricant that may collect in or onthe tube 18 will be thrown oil' the same into the crank case bycentrifugal force. This will follow even when the drill is turned inpositions with the crank journal 1]. downward. If the drill is stoppedin such position, the ball valve Qt) will tlllt'fillltlilt'tllly naiveto its seat I!) by gravity and close the tube 18 dotted lines in Fig. 2.

The provision of the tube 18 has also f another and important advantage.The tool can not, be completely tilled or packed with lubricant, soworking in an upright position there is a tendency for the lnln'icant to110- cumulate at the bottom of the crank case, leaving the upperconnecting rod bearing dry. When the tool isoperating in the positionshown in Fig. 1 the air current created by our invention moves towardthe top of the tool carrying the lubricant toward the upper connectingrod bearing and the crank journal 11. This action of the air has atendency of keeping the lubricant or a portion'of it toward the upperend of the tool, therefore maintaining" lubrication of the upperconnecting rod bearing and preventing it from becoming dry asheretofore. This is particularly important for the reason that the toolis generally operated downward or horizontally;

VS' hile we have shown and described herein in detail an air ventingmeans of our invention, it is of course to be understood that thedetails of structure and arrangement of parts may be variously changedand modified without departing from the spirit and scope of ourinvention.

lVe claim as our invention: v

1. In a piston actuated pneumatic tool, the combination with a crankcase, of a. crank shaft therein, and means includinga valve for ventingthe crank case through the crank shaft, said valve being opened bycentrifugal forces set up on rotation of said crank shaft.

2. In a piston actuated pneumatic tool, the combination with a' crankcase, of a crank shaft in said case and having an end journal supportedtherein, and means for venting the crank case through the end journal ofsaid shaft embracing an air outlet passage in the end journal, and a.valve controlling said passage, said valve being carried by said shaftand being automatically unseated by centrifugal forces set up on therotation of the shaft.

3. In a piston actuated pneumatic tool, the combination with a crankcase, of a crank shaft in said case and having an end journal supportedtherein, and means for venting the crank case through the end journal ofsaid shaft embracing an air outlet passage in the end journal, a tube inthe crank case and fixed to the shaft at the endjournal, said tubehaving a valve seat therein and opening into said outlet passage, and avalve in said tube and being automatically unscated by centrifugalforces set up on the rotation of said shaft. I

4. In a piston actuated pneumatic tool, the combination with a crankcase, of a crank shaft in said case and having an end journal therein,and means for venting the crank case through the end journal of saidshaft embracing an air outlet passage in the end journal. a tube inthecrank caseanr fixed to the shaft at the end journal. said tube having avalve seat therein and opening into said outlet passage, a valve in saidtube and being automatically unscated by centrifugal forces set up onthe rotation of said shaft, and a stop in the tube to limit theunseating movement of the valve.

5. In a piston actuated pneumatic tool. the combination with a crankcase having a tubular extension at one end,-of a crank shaft in saidcrank caseand having an end journal in said extension, said end journalhaving an air vent passage opening at its ends to the atmosphere and tothe interior of the crank case, respectively, a tube in said case andfixed to the shaft at said end journal, said tube having a valve seattherein and opening into said passage, and a valve in said tube andbeing automatically unseated by centrifugal forces set up on therotation of the crank shaft.

6.111 a. piston actuated pneumatic tool, the combination with .a crankcase having a tub ular extension at one end, of a crank shaft in saidcase and having an end journal in said extension, a cap closing theextension and provided with one or more air outlet ports, said endjournal having an air vent passage opening at its ends into the ca 0 andinto the crank case, respectively, a tu e in said case and fixed to theshaft at said end journal, said tube having a valve seat there in andopening in said passage, and a valve in said tube and beingautomatically unseated by centrifugal forces set up on rotation of thecrank.

7. In a piston actuated pneumatic tool, the combination with a crankcase having a tubular extension at one end, of a crank shaft in saidcrankcase and having an end journal in said extension, a cap closingsaid extension and provided with one or more air outlet ports, said endjournal having an air vent passage opening atits ends to the atmosphereand to the interior of the crank case, respectively, a thrust plate overthe outer end of said end journal and held stationary by said cap, atube carried by said plate and extending into the passage in said andjournal, a second tube in said case and fixed to. the crank shaft at theand journal, said tube having a valve seat therein and openin into saidpassage, and a valve in said second tube and being automaticallyunseated by centrifugal forces set up on rotation of said crank shaft.

8. In a piston actuated pneumatic tool,

.the combination with a crank casehaving a tubular e cnsion at one end,of a. crank shaft in said case and having an and journal in saidextension, an antifriction hearing between the extension and the andjournal, a cap closing the outer end of the extension and having one ormore air outlet ports, a, thrust plate held against the hearing by saidcap, and means for venting the case through the 0nd journal cml'iracingan air outl t sage in the end journal and opening at one end into thecrank case and at the other end into said up through said plate, and avalve for controlling said passage, said valve being.

shaft, said valve being opened by centrifugal forces set up on therotation of the crank shaft when the tool is held in any positionwherein gravity tends to close the. valve,

10. In a piston actuated pneumatic tool, the combination with a crankcase, of a crank shaft in said case and having its ends journaledtherein, a drill bit connected with one end of said crank shaft, andmeans for venting the crank case through the other end thereof. saidmeans including a 'alve being opened by centrifugal forces set up on therota tionoi' the crank shaft when the tool is held in any positionwherein gravity tends to close. the valve.

11. In a piston actuated pneumatic tool. the, combination with a crankcase, of a crank shaft in said case and having an end journal supportedtherein, a connecting rod connected with said shaft adjacent said endjournal, said end journal having an air out-. let passage having itsends opening to the atmosphere and to the case. respectively, a tube inthe crank case between the end journul and connecting rod and fixed tothe shaft at an inclination thereto. said tube having a valve seattherein and opening into said passage. and a valve in said tube andbeing aut-iimnitic-allv unseated by centrifugal forces set: up on therotation of said crank shaft.

In testimony that. we claim the foregoing as our invention, we altix oursignatures, this 5th day of November. 192?.

AXEL LEVEDAHL. REINHOLD A. NOR-LIN

